Air conditioning and water-harvesting

ABSTRACT

A system that provides both air conditioning and atmospheric water-harvesting has a refrigerant compressor and a refrigerant condenser that serve separate evaporators for the air conditioning subsystem and the atmospheric water-harvesting subsystem. The system can be controlled to operate in one mode that maximizes water production output or another mode that maximizes efficiency in terms of water output per unit of electricity consumed. The ability to switch between maximized water production and maximized water-production efficiency can be implemented in a stand-alone, dedicated water-harvesting system as well.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the priority benefit of U.S. provisional application No. 62/100,335 filed Jan. 6, 2015, the contents of which are incorporated herein in their entirety.

FIELD OF THE INVENTION

In general, the disclosure relates to air conditioning and atmospheric water-harvesting systems.

BACKGROUND OF THE INVENTION

Air conditioning is a well-known technology. In general, air is passed across the cooling coil (e.g., an evaporator) of a refrigeration circuit, where it is cooled and dried to a certain extent. After flash-evaporating in the evaporator and absorbing heat from the air flowing across the cooling cool as it does so, refrigerant in the refrigeration circuit is compressed to high pressure (and high temperature) in a compressor and then condensed back to its liquid phase in a condenser. A cooling medium (e.g. air or, in some systems, water or other liquid medium) flows past the condenser to cool the refrigerant. Heat that the refrigerant has absorbed from the air flowing across the cooling cool (as well as heat that has been imparted to the refrigerant due to compression) is transferred to the cooling medium and “disposed” of, e.g., by venting the cooling air to an outside environment, thereby allowing the refrigerant to continue cycling.

Atmospheric water-harvesting—that is, extracting moisture from the ambient atmosphere in sufficient quantities to provide for human/animal consumption—is a somewhat less common technology. Although atmospheric water-harvesting uses a cooling cycle that is, conceptually speaking, generally the same as or similar to the cooling cycle used for air conditioning, the operational points in terms of how much the ambient air needs to be cooled and how much air needs to be processed are relatively different as compared to the corresponding operational points for general air conditioning. As a result, air conditioning systems and atmospheric water-harvesting systems have historically been viewed as separate, independent systems and have been developed as such.

SUMMARY

The present disclosure features a more-unified system that provides for both air conditioning and atmospheric water-harvesting. In one aspect, a system according to this disclosure has a single compressor and condenser that serve both an air conditioning system, i.e., a system that is configured to operate at design points suitable for air conditioning, and an atmospheric water-harvesting system, i.e., a system that is configured to operate at design points suitable for atmospheric water-harvesting. Such a system has lower capital costs, operational costs, and space requirements than would be the case if separate air conditioning and water-harvesting systems were to be installed and utilized.

In another aspect, a system according to this disclosure is configured so that maximum water-production or maximum operational efficiency (in terms of water output per unit of electrical energy consumed) can be alternately selected. This may be done manually or according to some desired control scheme that is implemented by a controller, e.g., based on time of day when water consumption is greatest; time of day when energy rates (cost) are highest; etc. Furthermore, although this aspect of the invention can be utilized in a system that provides both air conditioning and water-harvesting, it can also be utilized in connection with a “stand-alone,” dedicated water-harvesting unit to provide generally similar benefits as in the case where it is utilized in connection with a combination air conditioning/water-harvesting system.

BRIEF DESCRIPTION OF THE FIGURES

These and other features will become clearer in view of the following disclosure, in which

FIG. 1 is a schematic, overall system diagram; and

FIG. 2 is a schematic, overall control diagram for the system shown in FIG. 1.

DETAILED DESCRIPTION

An air conditioning and water-harvesting system 10 is illustrated in FIG. 1. The system includes an air conditioning subsystem 12 (e.g., a residential or other-sized air conditioning system) and an atmospheric water-harvesting subsystem 14. In a generally conventional manner, the air conditioning subsystem 12 includes an evaporator 16 that is located within a duct 18 and a vent fan or other air-moving mechanism 20 that causes air to flow through the duct 18, from inlet end 22 to outlet end 24, and across the evaporator 16. Air exiting the duct 18 is provided to a space in which cooled, conditioned air is required, e.g., for the comfort of human or other animal occupants or, perhaps, for keeping electrical components from overheating. Suitably, the air conditioning subsystem 12 includes an air filter 26, to remove undesirable air-borne particles such as dust, mold, allergens, etc., as well as a condensate pan 28 to collect atmospheric moisture that may have condensed on and dripped off of the evaporator 16.

Similarly, in the specifically illustrated embodiment, the atmospheric water-harvesting subsystem 14 includes an evaporator 30 that is located within a duct 32 and a vent fan or other air-moving mechanism 34 that causes air to flow through the duct 32, from inlet end 36 to outlet end 38, and across the evaporator 30. As air flows across the evaporator 30, it cools substantially; as it does so, it becomes oversaturated with moisture, and moisture contained within the air will condense on the evaporator 30.

In more advanced configurations (not illustrated), the ducting arrangement of the atmospheric water-harvesting subsystem 12 could be configured as per the atmospheric water-harvesters disclosed in U.S. Pat. Nos. 7,954,335 and 8,627,673, the contents of both of which are incorporated by reference. According to those two patents, incoming air is precooled to varying degrees before it passes over the evaporator, with the amount of precooling that is provided varying inversely with ambient relative humidity levels since it is easier to extract moisture from air that is heavily laden with moisture such that precooling—with the operational costs or inefficiencies associated with it—becomes less important or beneficial.

Further still, in alternate embodiments (not illustrated), some of the cooled/chilled air immediately downstream of the evaporator 30 could be ported so as to combine with the cooled-air output from the air conditioning subsystem 12, thereby helping to cool the room or other environment that is being served by the air conditioning subsystem 12. Doing so would alleviate some of the cooling load being carried by the evaporator 16; on the other hand, system efficiencies attributable to further ducting and/or blowers/fans necessary to “shunt” that cooled/chilled, downstream air might counteract or even negate any such alleviation of the cooling load on the evaporator 16. Alternatively, cooled/chilled air immediately downstream of the evaporator 30 could be routed to the return air portion of the air conditioning subsystem 12, where it would help provide the required fresh air requirements for the subsystem. While ducting some of the cooled/chilled air coming off of the water-harvesting evaporator 30 into the room being air-conditioned, as mentioned above, contributes to overall “carrying capacity” of the air conditioning subsystem 12, “dumping” it into the return allows it to mix with room air and be distributed evenly through the existing air conditioning duct system.

As further illustrated in FIG. 1, the atmospheric water-harvesting subsystem 14 includes a condensate pan or other water-collecting device 40 to collect atmospheric moisture that will have condensed on and dripped off of the evaporator 30 and, suitably, an air filter 42 to remove undesirable air-borne particles such as dust, mold, allergens, etc. from the incoming moisture-supplying airstream, which particles could otherwise foul the evaporator and the product water. Water collected by the water-collecting device 40 is treated downstream in a water-purification system 44, which may include UV-sterilization, bacteriostatic treatment, re-mineralization, fluoride treatment, etc., to make the product water suitable for human consumption.

Furthermore, condensate that collects in condensate pan 28 in the air conditioning subsystem may be added to the water that is collected in the water-collecting device 40 to augment the overall water-production output of the system 10. Depending on the relative arrangement of the subsystems 12 and 14, the condensate could be transferred from condensate pan 28 to the water-collecting device 40 simply via gravity-feed or, as illustrated, via a water pump 46 and conduit 48.

With respect to further refrigeration-related components, the system 10 includes a variable-speed compressor 50 and a condenser 52. Suitably, the condenser 52 is located within the water-harvesting subsystem duct 32 so that air that has been cooled via the evaporator 30 to yield moisture will cool the condenser 52 and, hence, the refrigerant contained within it. (Depending on system configuration and/or ambient conditions, combining a portion of the air that has been cooled by the evaporator 30 with the cooled-air output from the air conditioning subsystem 12, as alluded to above, may—i.e., not necessarily will—reduce the condenser-cooling capability of the airflow through the water-harvesting subsystem to such an extent that so “shunting” the cooled air becomes undesirable.) Because the cooling air flowing across the condenser 52 will be heated significantly by the condenser 52, it is exhausted to an outside location instead of to an interior environment.

As illustrated schematically, refrigerant flows from the high-pressure discharge side 54 of the compressor 50 to the condenser 52 and then, from the condenser discharge, to a node or junction point 56. From the junction point 56, liquid-phase refrigerant is able to flow to both the air conditioning evaporator 16 and the water-harvesting evaporator 30. On/off (i.e., binary) solenoid valves 58 and 60 are provided to permit or prevent refrigerant from flowing to the evaporators 16 and 30, respectively.

Furthermore, an expansion valve 62 is located just upstream of the air conditioning evaporator 16, and an evaporator pressure regulator 66 is provided in the refrigerant line 68 downstream of the air conditioner evaporator 16. Together, the pressure regulator 66 and the expansion valve 62 provide fairly close or precise regulation or control over the degree of cooling provided by the air conditioning evaporator 16; this is desirable because over-cooling of the air-conditioned air can make it too cold and/or too dry for people within the air-conditioned space to be comfortable.

Similarly, an expansion valve 64 is located just upstream of the water-harvesting evaporator 30. However, in contrast to the air conditioning subsystem 12, no evaporator pressure regulator is provided in the disclosed embodiment to assist in regulating the behavior of refrigerant within the water-harvesting evaporator 30. This is because the air must be cooled to a significantly lower temperature in order to extract meaningful amounts of drinking water. (Air conditioning systems tend to produce air around 55 degrees Fahrenheit, which has a saturated humidity ratio of 64.6 grains/lb, whereas water-harvesting treats the air to closer to 38 degrees, which is saturated at 33.7 grains/lb, the difference in humidity representing a greater amount of water being collected by the water harvesting system.) Therefore, the water-harvesting evaporator can be operated “wide-open” to achieve maximum possible cooling of the air that flows over it.

By way of quantifying the configurations of the air conditioning and water-harvesting subsystems in term of their different operating points, the suction temperature for the air conditioning subsystem—i.e., the temperature of the refrigerant in the air conditioning evaporator at its saturation point—will be approximately 50° F. to 60° F., while the suction temperature for the water-harvesting subsystem will be closer to approximately 32° F. to 40° F.; these temperatures dictate or determine the respective evaporator surface temperatures, which will be similar to the refrigerant temperatures. Thus, with the overall system running optimally, the respective expansion valves will be set/configured to throttle to maintain these temperature rises from saturation temperature to the outlet of each respective evaporator. (As for refrigerant pressures within the evaporators, on the other hand, exact values will vary depending on the specific refrigerant that is used.)

Finally (in terms of the overall refrigeration cycle of the system 10), gaseous refrigerant from the air conditioning evaporator 16 combines with gaseous refrigerant from the water-harvesting evaporator 30 at junction or node-point 70. From there, the refrigerant returns to the suction side 72 of the compressor 50 to begin the cycle once again.

Furthermore, a number of refrigerant temperature and pressure sensors are located at various points within the system, and data from these sensors are used to regulate overall operation of the system 10. For example, as noted above, the system can be configured to operate selectively in one of two different modes—a first mode that is configured to produce a maximum amount of water per unit of time, and a second mode that is configured to maximize efficiency in terms of water produced per unit of electricity used—with the operating mode being either manually or, suitably, automatically selected by a controller. Thus, as further illustrated in FIG. 1, suction pressure sensor 74 is provided at, or just upstream of, the suction side 72 of the compressor 50; and high-side pressure sensor 76, used in connection with operating in the second, maximum-efficiency mode, is provided at, or just downstream of, the high-pressure discharge side 54 of the compressor 50. Pressure and temperature sensors 78 measure refrigerant pressure and temperature at the outlet of the water-harvesting evaporator 30, and these two values are used to regulate/control refrigerant flow through the evaporator 30 with a fairly high degree of precision as noted above.

On the other hand, corresponding pressure and temperature sensors are not illustrated in association with the air conditioning evaporator 16 since many common air conditioning systems (including, in particular, residential air conditioning systems) use a thermal expansion valve to regulate refrigerant flow through the evaporator. Such thermal expansion valves are fairly simple and are mechanically controlled via a refrigerant-temperature-sensing bulb, which provides a suitable degree of control for air conditioning purposes.

As illustrated in FIG. 2, the variable-speed compressor 50 is the plant that is controlled via the control system (programmable logic controller) 80 using the various parameter values measured by these sensors. Furthermore, as noted above, switch 82 by means of which the operating mode (maximum efficiency or maximum water production) is selected can be controlled by the logic controller 80 or, if desired, by a user-accessible manual override.

The foregoing disclosure is only intended to be exemplary. Departures from and modifications to the disclosed embodiments may occur to those having skill in the art. The scope of the invention is set forth in the following claims. 

1. A combination air conditioning and water-harvesting system, comprising: an air conditioning subsystem comprising an air conditioning evaporator; a water-harvesting subsystem comprising a water-harvesting evaporator; a refrigerant compressor; and a refrigerant condenser; wherein the refrigerant compressor and the refrigerant condenser compress and condense refrigerant that is supplied to both the air conditioning evaporator and the water-harvesting evaporator; and wherein the water-harvesting subsystem is configured to cool atmospheric air to a lower temperature than the air conditioning subsystem is configured to cool the atmospheric air, whereby the water-harvesting subsystem causes more moisture to condense out of the atmospheric air than the air conditioning subsystem does.
 2. The air conditioning and water-harvesting system of claim 1, wherein the system is configured to selectively operate in one of two modes, the two modes comprising a maximum-water-production mode and a maximum-efficiency mode.
 3. A water-producing device, comprising: a refrigerant evaporator; a variable-speed refrigerant compressor and a refrigerant condenser which, respectively, compress and condense refrigerant that is subsequently supplied to the evaporator; and a switch that controls operation of the device such that the device operates in one of two modes comprising a maximum-water-production mode and a maximum-operational-efficiency mode.
 4. The water-producing device of claim 3, further comprising a control module that controls the mode in which the device operates.
 5. The water-producing device of claim 3, wherein the switch is manually operable so as to manually select the mode in which the device operates.
 6. The water-producing device of claim 3, further comprising a control module that controls the mode in which the device operates, wherein the switch is further configured to permit manual override of the operating mode selected by the controller so as to permit manual selection of the mode in which the device operates. 